However, he would leave the UFNR as a result of the failure of the electoral alliance with the radicals of Alejandro Lerroux in the 1914 elections.

[5] During the Spanish crisis of 1917, he would publish a famous article in La Lucha, "¿Qué espera el Rey?

[3] He was one of the main figures of the Assembly of Parliamentarians [es] and of the preparation of the 1917 Spanish general strike led by PSOE and UGT, among others.

In 1928, he published his essay Libertad y Autoridad in the Javier Morata Pedreño Vanguard Library collection in Madrid.

[8] Marcelino Domingo was Minister of Public Instruction during the First Biennium of the Republic, between April and December 1931.